Vocabulary

Absorption Lines

Thin dark lines across a spectrum which indicate the presence of chemical element in the light source.

Accretion Disk

A structure formed by material being drawn into a rapidly rotating black hole.

Asteroid

A lump of rock orbiting the sun. Most asteroids are found in a narrow belt situated between Mars and Jupiter.

Astronomy

A scientific study of objects in space.

Atmosphere

Layer of gases surrounding a planet, moon, or star.

Axis (of spin)

An imaginary line through a rotating object, around which the object rotates.

Big Bang

The explosion that created the universe about 15 billion years ago.

Big Crunch

One possible future end for the universe-the big bang in reverse.

Black hole

An infinitely dense object formed initially by the collapse of a massive star. The gravity of a black hole is so strong that not even light can escape from it.

Celestial Equator

A projection of Earth’s equator out into space, used as a baseline for positioning stars.

Celestial pole

Projection of Earths north or South Pole into space, for use as a reference point.

Celestial sphere

The appearance of the stars from Earth- as though they were set into a black sphere around the planet.

Chromosphere

The Sun’s inner atmosphere.

Cluster

A grouping of stars or galaxies held by gravity.

Comet

An object composed of snow and dust that orbits the sun. If a comets approaches the sun it forms a tail of gas and dust particles.

Constellation

A grouping of bright stars seen in Earth’s sky. In most cases the grouping is a trick of perspective and the stars are a long way apart.

This is the constellation Ursa Major, what we usually call The Big Dipper.

Co/orbital

Sharing an orbital path with another object.

Core

The central region of a planet, star, or galaxy.

Corona

The sun's outer atmosphere.

Crater

Circular depression in the surface of a planet or a moon caused by a meteorite impact.

Crust

The surface layer of a rock planet or moon.

Eclipse

The effect produced when one object in space passes in front of another and obscures it.

This picture shows a solar eclipse, which is when the moon passes in between the earth and the sun, blocking the sun from view.

Ecliptic

The sun's apparent path around the celestial sphere during a year.

Flyby

The path of a space probe that obtains information by flying past, or orbiting, a moon or planet.

Galaxy

A large grouping of stars held together by gravity. Galaxies can be spiral, elliptical (oval) , or irregular in shape.

Gravity

An attractive force that is a property of mass.

Light year

The distance traveled by light in one year -used to measure distance between stars and galaxies.

Orbit

The curved path of an object or spacecraft around a star, planet, or moon.

This GIF shows the earth in its orbit around the sun. Earth is orbiting the sun.

Solar System

The collection of planets and moons that go around (orbit) the sun, along with smaller bodies such as asteroids, meteoroids, and comets.

This picture shows our solar system.